1. Field of the Invention
The present invention relates to magnetic recording media, and more specifically, it relates to systems for controllably patterning magnetic recording disks.
2. Description of Related Art
Magnetic recording disks are required to have areas which are controllably textured, especially areas where the transducing head is allowed to contact the disk. The texturing reduces the friction encountered by the head during the "spin up" allowing more rapid disk activation and reduced wear on the heads. In current manufacturing processes, the texturing is accomplished in an off line step prior to the main manufacturing which occurs in the disk sputtering system. This texturing is currently done with an abrasive grit based process and requires costly cleaning of the disk prior to insertion into the sputtering system.
A process using a low power focused laser output to generate texture spots has been discussed (Ranjan et al., U.S. Pat. No. 5,062,021) but no practical means of implementing the process, which requires as many as 200,000 texture spots on a disk, was discussed. In this process, the short pulse output (15 ns) of a low power laser (4 .mu.J) is focused to a spot size of roughly 10 .mu.m diameter. The laser energy locally heats the substrate and produces a small crater with a rim rising above the substrate surface. The integrated surface area projected locally by the rims is significantly less than that of the polished substrate. Consequently friction is significantly reduced and disk performance and lifetime greatly improved.
It is desirable to build a disk marking process station as a stand alone system and/or to incorporate a laser marking process as a station in a disk sputtering system process. However, so as not to impede the throughput rate of the system, the roughly 200,000 texture spots need to be created in less than 6 seconds. A spot by spot marking of the texture pattern, as discussed in Ranjan et al., is impractical.